The Gathering Storm

The series' storyline has been leading up to the "Last Battle" (Tarmon Gai'don)—a fight between the forces of Light and Shadow. According to prophecy in the series the primary protagonist Rand al'Thor, as the Dragon Reborn, will "fight the [battle]", and must be present for the forces of Light to have a chance at winning and stopping the being known as the Dark One, the primary antagonist, from escaping his prison.
The Gathering Storm follows many plot threads but focuses on two characters, Rand al'Thor and Egwene al'Vere. While it follows al'Thor's attempts to unite and rally the world's forces for the Last Battle, it also addresses his struggle with his sanity, caused by the corruption of his mind from the use of the male half of the One Power. The unification of the White Tower, the headquarters of the female users of the One Power known as Aes Sedai, is addressed from al'Vere's perspective, as well as the exposure of the Black Ajah, a secretive and opposing faction within the story. While the stories of other main characters such as Perrin Aybara and Mat Cauthon are briefly touched upon, they have little bearing on the main plot line. Some main characters such as Elayne Trakand and Lan Mandragoran do not appear at all, but are referred to.

Synopsis

==== Rand al'Thor ====
As Rand's story begins, he is restoring order in the nation of Arad Doman while searching for Graendal, one of the Dark One's favored servants known as the Forsaken. The Aes Sedai work with Rand to interrogate Semirhage, another Forsaken captured at the end of Knife of Dreams. After being freed by her allies, Semirhage is given a Domination Band, an item used to control male channelers, and locks it around Rand's neck. She and Black Ajah sister Elza Penfell use it to make him torture and attempt to kill his lover, Min Farshaw. Unable to channel, he reaches out and inexplicably accesses the True Power, a different power normally only granted by the Dark One, using it to free himself and kill Semirhage and Elza. After this, he resolves to make himself harder and emotionless. He banishes his adviser Cadsuane Melaidhrin for not securing the Domination Band, promising to kill her if he sees her face again.
Rand meets with the Seanchan, a civilization that invaded the continent earlier in the series. Their leader Tuon rejects Rand's offer of a truce after sensing a dark aura that emanated from Rand after he channeled the True Power. Following the meeting, Tuon declares herself Empress and prepares a surprise attack against the White Tower.
Graendal's hiding place is traced to a remote palace. Confirming her presence, Rand uses the Choedan Kal, a powerful magical artifact, to eliminate the entire building with balefire, a magic that wipes the target from time. This horrifies Min and Nynaeve al'Meara and they turn to Cadsuane for help. Giving up on saving Arad Doman from the Seanchan and starvation, Rand returns to the city of Tear.
Nynaeve, under the instruction of Cadsuane, locates Tam al'Thor, Rand's father, who meets with Rand in an attempt to break his emotional isolation. Rand becomes angry when he learns that Tam was sent by Cadsuane, nearly killing his father before fleeing in horror at what he had almost done. Rand Travels to the Seanchan-held city of Ebou Dar, intending to destroy their entire army, but he becomes reluctant to act after seeing how peaceful the city is. Nearly mad with rage and grief, he Travels to the top of Dragonmount, the location where he killed himself in a past life. Angry at the futility of life bound to the Wheel, he uses the Choedan Kal to draw enough power to destroy the world. Lews Therin, a voice in Rand's head from his past life, suggests that by being reborn one has the opportunity to do things right. Agreeing, Rand turns the power of the Choedan Kal against itself, destroying it. Rand is finally able to laugh again.

Egwene al'Vere

The second main plot thread follows Egwene al'Vere, leader of the rebel faction of Aes Sedai. After her capture by the White Tower in the previous book, Egwene works to undermine Elaida a'Roihan's rule and mend the strife it is causing in the White Tower. She is initially granted freedom of the tower as novice, but after publicly denouncing Elaida, Elaida names her a follower of the Dark One, and orders her imprisonment. When Elaida fails to prove her accusation, Egwene is released.
Egwene returns to her room to find Verin Mathwin, who announces that she is of the Black Ajah. Taking advantage of a loophole in the oath Verin had sworn that she could not betray them "until the hour of my death", she fatally poisons herself, allowing her to use her last hour to reveal everything she has learned to Egwene. Verin explains that although she was forced to swear to them or face death, she used the position to research the Ajah. She gives Egwene a journal detailing the group's structure and nearly every member before succumbing to the poison.
When the Seanchan attack the White Tower, its fractured state prevents an effective defense. Many Aes Sedai are captured or killed until Egwene, leading a group of novices, succeeds in driving them off. Siuan Sanche, Gawyn Trakand, and Gareth Bryne mount a rescue of Egwene. They find her so exhausted that she cannot protest when they extract her against her orders. After awakening in the camp, she argues that they may have ruined her chances to gain credit in the Tower for the defeat of the Seanchan.
Egwene begins to expose the Black Ajah among the rebels, requiring every sister to re-swear her allegiances. Fifty sisters are exposed and executed, while twenty are able to escape. Taking advantage of the weakened White Tower defenses following the Seanchan raid, the rebels prepare an immediate attack. Just before the attack is mounted, the Tower Aes Sedai announce that Elaida was captured in the Seanchan raid, and that they would have Egwene as their leader, the Amyrlin Seat. The rebels return and they begin rebuilding the Tower.